Encyclopedia of

Staphylococcal infections

Definition

Staphylococcal (staph) infections are communicable diseases caused by
certain bacteria and generally characterized by the formation of
abscesses. They are the leading cause of primary infections originating in
hospitals in the United States.

Description

Classified since the early twentieth century as among the deadliest of all
disease-causing organisms, staphylococcal bacteria exist on the skin or
inside the nostrils of 20 to 30 percent of healthy people. It is sometimes
found in breast tissue, the mouth, and the genital, urinary, and upper
respiratory tracts.

Staph bacteria are usually harmless; however, when an injury or a break in
the skin enables the organisms to invade the body and overcome the
body's natural defenses, consequences can range from minor
discomfort to death.

Demographics

Infection is most apt to occur in newborns; children whose immune systems
have been undermined by radiation treatments,
chemotherapy
, or medication; those with surgical incisions or skin disorders; and
among people with serious illnesses such as
cancer
, diabetes, and lung disease. Children are also more at risk for staph
infections if they have HIV/AIDS or other diseases that compromise immune
function, have a catheter or implanted prosthetics, are hospitalized, have
open
wounds
, or live in close quarters with a large group of others. It is not clear
exactly how many staph infections occur each year, but it is the most
common infection that begins in the hospital.

Causes and symptoms

Staph infections produce pus-filled pockets (abscesses) located just
beneath the surface of the skin or deep within the body. A localized staph
infection is confined to a ring of dead and dying white blood cells and
bacteria. The skin above it feels warm to the touch. Most of these
abscesses eventually burst, and pus that leaks onto the skin can cause new
infections.

A small fraction of localized staph infections enter the bloodstream and
spread through the body. In children, these systemic (affecting the whole
body) or disseminated infections frequently affect the ends of the long
bones of the arms or legs, causing a bone infection called osteomyelitis.
Other abscesses that can develop from staph infection include those of the
brain, heart, kidneys, liver, lungs, or spleen.

Staphylococcus aureus

Named for the golden color of the bacteria grown under laboratory
conditions,
Staphylococcus aureus
is a hardy organism that can survive in extreme temperatures or other
inhospitable circumstances. About 70 to 90 percent of the population carry
this type of staph in their nostrils at some time in their lives. Although
present on the skin of only 5 to 20 percent of healthy people, as many as
40 percent of individuals carry it elsewhere, such as in the throat,
vagina, or rectum, for varying periods of time, from hours to years,
without developing symptoms or becoming ill.

S. aureus
flourishes in hospitals, where it infects healthcare personnel and
infects patients who have had surgery, have open wounds, have acute
dermatitis
, insulin-dependent diabetes, or dialysis-dependent kidney disease, or who
receive frequent allergy-desensitization injections. Staph bacteria can
also contaminate bedclothes, catheters, and other objects.

S. aureus
causes a variety of infections. Boils and inflammation of the skin
surrounding a hair shaft (folliculitis) are the most common. Toxic shock
(TSS) and scalded skin syndrome (SSS) are among the most serious.

TOXIC SHOCK
Toxic shock syndrome
is a life-threatening infection characterized by severe
headache
,
sore throat
,
fever
as high as 105°F (40.5°C), and a sunburn-like rash that spreads
from the face to the rest of the body. Symptoms appear suddenly. They also
include
dehydration
and watery
diarrhea
.

Inadequate blood flow to peripheral parts of the body (shock) and loss of
consciousness occur within the first 48 hours. Between the third and
seventh day of illness, skin peels from the palms of the hands, soles of
the feet, and other parts of the body. Kidney, liver, and muscle damage
often occur.

SCALDED SKIN SYNDROME
Rare in adults and most common in newborns and other children under the
age of five, scalded skin syndrome originates with a localized skin
infection. A mild fever and/or an increase in the number of
infection-fighting white blood cells may occur.

A bright red rash spreads from the face to other parts of the body and
eventually forms scales. Large, soft blisters develop at the site of
infection and elsewhere. When they burst, they expose inflamed skin that
looks as if it had been burned.

inflammation of tissue that encloses and protects the spinal cord and
brain (meningitis)

inflammation of bone and bone marrow (osteomyelitis)

pneumonia

Other strains of staphylococci

S. EPIDERMIDIS
Capable of clinging to tubing (such as that used for intravenous
feeding), prosthetic devices, and other non-living surfaces,
S. epidermidis
is the organism that most often contaminates devices that provide direct
access to the bloodstream.

The primary cause of bacterial infection in hospital patients, this strain
of staph is most likely to infect cancer patients, whose immune systems
have been compromised and high-risk newborns receiving intravenous
supplements.

S. epidermidis
also accounts for two of every five cases of prosthetic valve
endocarditis. Prosthetic valve endocarditis is inflammation that occurs as
a complication of the implantation of an artificial valve in the heart.
Although contamination usually occurs during surgery, symptoms of
infection may not become evident until a year after the operation. More
than half of the patients who develop prosthetic valve endocarditis die.

Causes and symptoms

Staph bacteria can spread through the air, but infection is almost always
the result of direct contact with open sores or body fluids contaminated
by these organisms. Staph bacteria often enter the body through inflamed
hair follicles or oil glands. Or they penetrate skin damaged by
burns
, cuts and scrapes, infection, insect
bites
, or wounds.

Multiplying beneath the skin, bacteria infect and destroy tissue in the
area where they entered the body. Staph infection of the blood
(staphylococcal bacteremia) develops when bacteria from a local infection
infiltrate the lymph glands and bloodstream. These infections, which can
usually be traced to contaminated catheters or intravenous devices, cause
persistent high fever. They may cause shock. They also can cause death
within a short time.

When to call the doctor

The following are common symptoms of staph infection:

pain or swelling around a cut or an area of skin that has been scraped

boils or other skin abscesses

blistering, peeling, or scaling of the skin (This symptom is most common
in infants and young children.)

enlarged lymph nodes in the neck, armpits, or groin

A
family
physician should be notified whenever the following symptoms are present:

Lymph nodes in the neck, armpits, or groin become swollen or tender.

An area of skin that has been cut or scraped becomes painful or swollen,
feels hot, or produces pus. These symptoms may mean the infection has
spread to the bloodstream.

A boil or carbuncle appears on any part of the face or spine. Staph
infections affecting these areas can spread to the brain or spinal cord.

A boil becomes very sore. Usually a sign that infection has spread, this
condition may be accompanied by fever, chills, and red streaks radiating
from the site of the original infection.

Boils develop repeatedly. This type of recurrent infection could be a
symptom of diabetes.

Diagnosis

Blood tests that show unusually high concentrations of white blood cells
can suggest staph infection, but diagnosis is based on laboratory analysis
of material removed from pus-filled sores and on analysis of normally
uninfected body fluids such as blood and urine. Also, x-rays can enable
doctors to locate internal abscesses and estimate the severity of
infection. Needle biopsy (removing tissue with a needle, then examining it
under a microscope) may be used to assess if any bones are infected.

Treatment

Superficial staph infections can generally be cured by keeping the area
clean, using soaps that leave a germ-killing film on the skin, and
applying warm, moist compresses to the affected area for 20 to 30 minutes
three or four times a day.

Severe or recurrent infections may require a seven to 10 day course of
treatment with penicillin or other oral
antibiotics
. The location of the infection and the identity of the causal bacteria
determine which of several effective medications should be prescribed.

In case of a more serious infection, antibiotics may be administered
intravenously for as long as six weeks. Intravenous antibiotics are also
used to treat staph infections around the eyes or on other parts of the
face.

Surgery may be required to drain or remove abscesses that form on internal
organs or on shunts or other devices implanted inside the body.

Alternative treatment

Alternative therapies for staph infection are meant to strengthen the
immune system and prevent recurrences. Among the therapies believed to be
helpful for the person with a staph infection are
yoga
(to stimulate the immune system and promote relaxation), acupuncture (to
draw heat away from the infection), and herbal remedies. Herbs that may
help the body overcome, or withstand, staph infection include the
following:

Garlic (
Allium sativum
). This herb is believed to have antibacterial properties. Herbalists
recommend consuming three garlic cloves or three garlic oil capsules a
day, starting when symptoms of infection first appear.

Cleavers (
Galium aparine
). This anti-inflammatory herb is believed to support the lymphatic
system. It may be taken internally to help heal staph abscesses and
reduce swelling of the lymph nodes. A cleavers compress can also be
applied directly to a skin infection.

Goldenseal (
Hydrastis canadensis
). Another herb believed to fight infection and reduce inflammation,
goldenseal may be taken internally when symptoms of infection first
appear. Skin infections can be treated by making a paste of water and
powdered goldenseal root and applying it directly to the affected area.
The preparation should be covered with a clean bandage and left in place
overnight.

Echinacea (
Echinacea
spp.). Taken internally, this herb is believed to have antibiotic
properties and is also thought to strengthen the immune system.

Thyme (
Thymus vulgaris
), lavender (
Lavandula officinalis
), or bergamot (
Citrus bergamot
) oils. These oils are believed to have antibacterial properties and may
help to prevent the scarring that may result from skin infections. A few
drops of these oils are added to water and then a compress soaked in the
water is applied to the affected area.

Tea tree oil (
Melaleuca
spp.). Another infection-fighting herb, this oil can be applied
directly to a boil or other skin infection.

Prognosis

Most healthy people who develop staph infections recover fully within a
short time. Others develop repeated infections. Some become seriously ill,
requiring long-term therapy or emergency care. A small percentage die.

Doctors and researchers are becoming increasingly concerned about staph
infections that are resistant to antibiotics. A bacterium that is
considered resistant is one that can no longer be treated effectively
using the antibiotics that are commonly prescribed for that type of
infection. Resistant staph infections can usually be treated effectively
with other antibiotics. Children who are most at risk for resistant staph
infections are those who have been in the hospital or have serious
underlying medical conditions. According to the Centers for Disease
Control, although it is not clear how many cases of resistant staph
infections occur each year, they are thought to be very rare. They
recommend
treating all infections promptly and only prescribing antibiotics when
there is an underlying bacterial cause for the disease (antibiotics are
not effective against viruses) to help reduce the occurrence of bacteria
becoming resistant to antibiotics.

Prevention

Healthcare providers and patients should always wash their hands
thoroughly with warm water and soap after treating a staph infection or
touching an open wound or the pus it produces. Pus that oozes onto the
skin from the site of an infection should be removed immediately. This
affected area should then be cleansed with antiseptic or with
antibacterial soap.

To prevent infection from spreading from one part of the body to another,
it is important to shower rather than bathe during the healing process.
Because staph infection is easily transmitted from one member of a
household to others, towels, washcloths, and bed linens used by someone
with a staph infection should not be used by anyone else. They should be
changed daily until symptoms disappear, and laundered separately in hot
water with bleach. Children should frequently be reminded not to share
brushes, combs, or hair accessories.

Parental concerns

Staph infections are most likely to occur after a child has had surgery or
a wound of some kind. A good way to help prevent staph infections of
wounds is to keep the wound clean and dry. Children who have staph
infections, especially skin infections, should be kept away from others
whom they are likely to infect, and their bedding, clothes, and other
things that may have touched the wound should be cleaned with hot soapy
water and bleach.

KEY TERMS

Abscess
—A localized collection of pus in the skin or other body tissue
caused by infection.

Endocarditis
—Inflammation of the inner membrane lining heart and/or of the
heart valves caused by infection.